Colonizing and Terraforming Venus

While talk about colonizing the solar system has dominated the news lately with Elon Musk's visionary plan for Mars, another potential target for colonization might not be getting the attention it deserves. There are reasons for this, the planet's surface is a truly hellish mix of extremely hot temperatures and sulfuric acid. That planet is Venus, and while at first glance it doesn't look like a good candidate for colonization, there are some surprisingly attractive attributes to this world that may eventually make it worthwhile.

As Elon Musk points out, we need to become a multiple planet species if we wish the human race to survive any calamity that might cause our extinction such as an asteroid impact. Sooner or later, something bad will happen and a second planet would serve as insurance against extinction. But why not a third planet? And why not Venus?

If it weren't for the hostile surface conditions, Venus would be the obvious choice for colonization as opposed to Mars. Surface conditions aside, Venus could be called a sister planet to earth. With Mars, due to its smaller size, we aren't yet certain that humans will avoid bone decalcification due to a lack of gravity. This is not the case for Venus, which is almost the same size as earth with comparable gravity probably eliminating decalcification as a problem for colonization entirely.

Venus is also closer than Mars, which favors both transport and communications. Launch windows for Mars occur every 780 days as the planet passes close by. For Venus, this is only 584 days. Flight times are also going to be shorter than for Mars. Like Mars, Venus' atmosphere is mostly carbon dioxide. If you filter out the sulfuric acid, you can use that carbon dioxide to grow plants. And there is a zone on Venus that looks far more attractive than its surface.

This zone, which is about 31 miles in the atmosphere above the planet's surface, has a different composition due to the fact that nitrogen and oxygen are lighter than carbon dioxide. This means that if you fill a balloon with earth air, it will float in this region. The temperature here is nicer as well, about 75 °C or 167 degrees. If you go a bit higher, say 5 kilometers, it drops to a comfortable 81 degrees Fahrenheit. This zone also favors colonization in that it also happens to be about the same air pressure that we experience here on earth. Handy indeed. And, the atmosphere above this sweet spot naturally shields out cosmic radiation roughly comparable to how Earth's atmosphere does.

That's a lot of points in Venus' favor. But the obvious problem here is that you'd have to suspend your colony high up in the atmosphere of Venus and make sure it stays there. But this may not be as hard as you might think. As I mentioned, breathable earth air is a lifting gas on Venus, much like helium is here. That means that if you were inside a balloon on Venus, you could easily live, and so long as that balloon doesn't pop, you would be in much safer natural conditions than one would be on the surface of Mars.

If your balloon sprung a leak, for example, there would be no explosive decompression due to the similar air pressures inside and out. You would have plenty of time to patch it up. Similarly, you would not require pressurized space suits, just protective ones to keep out the sulfuric acid and of course a breathing apparatus and protection from the heat, which isn't that big of a deal.

Now, it's pretty windy up there, often reaching over 200 miles per hour, but there's also nothing to run into so you could let the balloon colony move with the winds, which would reduce structural stress.

There are cons to the idea of colonizing Venus as well. It has no oxygen, so it would have be manufactured from carbon dioxide. It also has basically no water, meaning you'd have to get that from the sulfuric acid. Retrieving anything from the surface would difficult given the surface conditions. And you would need some serious corrosion protection in all elements of your colony. Add that to the fact that Venus rotates very slowly compared to earth, its day is 243 earth days long. In fact, its day is longer than its year, which is only 224 earth days.

But if we did colonize Venus, might we be able to terraform it and make it earth-like? The answer is yes, it's theoretically possible. In fact, Paul Birch put forth just such a plan that would allow the planet to be terraformed in just two centuries. Humans have taken on huge projects that took even longer than that before, often it would take 500 years or more to build a medieval gothic cathedral. So two centuries is not that long of a time for a project.

Birch's plan envisions putting a thin solar shade perhaps made of Mylar or a similar substance in the line of sight between the sun and Venus and reduce the temperature of the atmosphere. As the planet cools, the high pressures will cause the carbon dioxide to liquefy and rain onto the planet as oceans. Then, as the cooling continues, the oceans freeze and become dry ice. You then cover the frozen oceans over with a thermally insulating layer and you've got a fresh planet to work with where the amount of carbon dioxide in the protoatmosphere can be controlled.

To make it earth-like, you would first need a lot of water. The problem there is that water is hard to transport, so it's better to make it onsite. To do this, you need hydrogen, which is something Venus doesn't have much of. But the gas giant planets do and it's possible to mine it from them.

Transporting that hydrogen could be accomplished with a mass driver system, you just electromagnetically fling loads of the material to Venus. In fact, it may eventually be the case that we build mass drivers on many bodies in the solar system to move materials around.

An alternative to securing the water which is much faster is to simply crash an icy moon into Venus in a controlled fashion. This is harder, but also surprisingly possible through using the gravity of bodies such as Saturn and its moons to move large objects around.

Then you need the oxygen. This can come from our frozen carbon dioxide oceans readily either by chemically releasing it or using algae or a similar bioengineered method taking advantage of photosynthesis.

The last major problem is Venus's slow rotation. One approach to this would be to speed the planet up, and there are theoretical ways to do that, but it would seem to make more sense to just simulate a 24 hour day. Birch suggests that we use a soletta, a kind of rotating mirror in polar orbit to create the illusion of a day. Alternatively, solar mirrors can both shade the lit side of Venus and reflect light to the dark side as needed to create a suitable day.

While all of this may seem beyond reach, at least in theory it's actually something we could do right now. Birch lays out in his paper that we could begin colonization of the atmosphere and terraforming efforts in 2030 and have a fully habitable second earth by 2250. It would be difficult and expensive, there's no doubt of that, but it is doable and may not be so expensive as we expand out and begin colonizing other areas of the solar system at the same time. Especially if Elon Musk's plan for Mars comes to fruition, a big part of that is that the entire solar system becomes accessible.

So both colonizing Venus' atmosphere and eventually terraforming are possible and perhaps even advantageous. And with all the buzz surrounding Elon Musk's bold plan to colonize Mars, I hope the idea of colonizing the solar system catches fire and some day Venus too may also be a self-sustaining home for humankind.